The invention is in the microelectronics field. The invention particularly concerns emitters and devices incorporating emitters.
Controllable electron sources, such as sub-micron cold cathode emitters, have a wide range of potential applicability in the microelectronics field. These electron sources find particular use in displays, analytical instruments, sensors, micro-array electron beam lithography tools, and memory devices. Electron sources are often grouped according to whether they are heated sources or cold sources. Heated sources or cathodes are usually mixed oxide thermionics or Schottky type devices. Cold sources or cathodes include radioactive decay sources, sharp point devices such as xe2x80x9cSpindtxe2x80x9d tips, silicon etched tips, carbon nanotubes and flat emitters. Non-radioactive cold cathodes emit electrons by extracting electrons from a source layer by the application of a sufficient electric field. Cold cathodes emit electrons by quantum tunneling of electrons.
Emitters require architectures that have, at a minimum, three layers for enabling controlled electron emissions, which form a basis for creation of a range of useful electrical and optical effects. These layers include an electron source layer, an insulator layer, and a conducting layer or extractor. A voltage source connected between the conducting layer and the source layer creates an electric field which causes electron emissions from the source layer.
As emitter size has become smaller and smaller to facilitate integration with IC circuits and devices, problems have occurred with the fabrication of submicron cold cathode emitters. Emitter formation processes typically produce emitter structures having varied heights, shapes and locations. Some emitter structures may be shorted or remain unexposed as a result of the varied heights, shapes and locations.
According to the invention, an emission device for generating an electron emission current comprises a plurality of electron emitter structures having varied geometries. Each of the electron emitter structures includes one or more tunneling sites which provide an electron emission current. The emission device further includes a conducting layer that can be voltage biased relative to the plurality electron emitter structures to induce the electron emission current from tunneling sites of the electron emitter structures. The conducting layer includes openings at the tunneling sites to facilitate electron emission.